Trans Boundary Environmental Harm and State Responsibility: A Study Through the Lens of International Law

Abstract

Trans-boundary environmental harm remains a persistent and complex challenge in international law, testing the limits of state sovereignty and collective responsibility. Classic principles such as the “no-harm” rule – first articulated in the Trail Smelter arbitration and international frameworks like the 1972 Stockholm Declaration and 1992 Rio Declaration affirm that states must ensure activities within their jurisdiction do not damage the environment of other states. Yet despite a proliferation of multilateral environmental agreements and guiding norms, disputes endure over accountability, reparations and enforcement. This paper examines the doctrinal underpinnings of state responsibility for trans-boundary environmental damage under customary international law, treaty law and soft-law instruments, alongside key judicial decisions and emerging developments. The analysis highlights the urgent need for clearer liability standards, stronger enforcement mechanisms, and innovative approaches from corporate accountability, to the recognition of ecocide and to address environmental harms of cross borders. In an era of climate change and global ecological interdependence, international law must evolve a more coherent and enforceable architecture that reconciles state sovereignty with the shared duty to safeguard the global commons for present and future generations.